Device for high voltage gas-filled rectifiers



y 15, 1962 c. DILLON ET AL 3,035,204

DEVICE FOR HIGH VOLTAGE GAS-FILLED RECTIFIERS Filed May 25, 1960 2 Sheets-Sheet 1 y 1962 c. DILLON ET AL 3,035,204

DEVICE FOR HIGH VOLTAGE GAS-FILLED RECTIFIERS Filed May 25,1960 2 Sheets-Sheet 2 v V NTOR. Char/Es flI /OIV Gan/NH! E y 737717 1 United States Patent Sweden Filed May 23, 1960, Ser. No. 31,005 Claims priority, application Sweden June 3, 1959 3 Claims. (Cl. 315-36) The present invention relates to a device for a high voltage gas-filled rectifier provided with a number of intermediate electrodes connected to a voltage divider consisting of resistors and capacitors, said voltage divider being inserted between the anode and the cathode of the rectifier.

It has been observed that in gasfilled rectifiers with voltage dividers of this type flash-over may arise between the connections between the intermediate electrodes and the voltage divider and over the components of the voltage divider. It is observed that one of the reasons for this is that it takes a certain time for the arc during the ignition of a rectifier of said type to extend from the cathode via the intermediate electrodes to the anode. During ignition a still greater part of the total voltage difference between the anode and the cathode thus will be concentrated in the part of the voltage divider nearest to the anode so that in this part voltage concentrations will arise between the connections between the intermediate electrodes and the voltage divider. These great voltage influences may cause flash-over between the connections between the intermediate electrodes and the voltage divider owing to the fact that flash-over occurs more rapidly in the air outside the rectifier than inside the rectifier. Another reason for flash-over occurring is that during normal operation of the rectifier interruptions in the arc could arise, so-called quenchings between some of the intermediate electrodes. In this case the great load current through the rectifier tends to pass through that part of the voltage divider which is connected between said intermediate electrodes. Consequently, owing to the very great current, great over voltages will arise over this part of the voltage divider, which may give flashover.

The risk and consequence of such flash-over are very much decreased by the present invention, which is substantially characterised in that voltage dependent resistors are inserted between at least some of the connections between the intermediate electrodes, and the voltage divider. Through these voltage dependent resistors, the over voltages over the voltage divider are limited so that no flash-over will arise. These voltage dependent resistors, however, could not all alone protect the voltage divider against over voltages arising at a quenching of the arc during normal operation of the rectifier. This is, however possible if according to the invention, spark gaps are inserted over the voltage dependent resistors and possibly even between such connections between the intermediate electrodes and the voltage divider where no voltage dependent resistors are inserted. Certainly it is normally not possible to protect a voltage dependent resistor by means of a spark gap parallel connected to the resistor, but in this case, however, it is possible owing to the very great current tending to pass through the voltage dependent resistor and the voltage divider at quenching of the arc. Further, according to the invention, the bodies for connection of the voltage dependent resistors and the resistors and the capacitors of the voltage divider could be suitably so shaped that they serve as mechanical as well as electrical connections of the components, and besides this, as spark gap electrodes for the spark gaps between the components.

The invention will be further explained in the following with reference to the accompanying drawings in which by way of example, FIGURE 1 shows a diagram of the connection for a device according to the invention, FIG- URES 2 and 3 show the constructive shape of the device according to FIGURE 1, and FIGURE 4 the performance of a body for connection of the different components in the voltage divider and the voltage dependent resistors.

FiGURE 1 shows a high voltage gas-filled rectifier 1 with an anode 2, a cathode 3 and a number of intermediate electrodes 4. The intermediate electrodes 4 are connected to a voltage divider inserted between the anode 2 and the cathode 3. The voltage divider consists partly of a purely resistive voltage divider consisting of resistors 5 and a combined capacitor-resistor chain consisting of capacitors 6 and resistors 7. The capacitor-resistor chain and the resistor chain 5 are parallel connected and at the same time connected by a number of transverse connections and connected to the intermediate electrodes 4, in some cases via series resistors 8. Between some of the connections between the intermediate electrodes and the voltage divider voltage dependent resistors 9 are inserted limiting the voltage between the intermediate electrodes during the ignition so that no flash-over arises. Further, spark gaps 10 are inserted between the connections between the intermediate electrodes 4 and the voltage divider, which spark gaps contribute to protecting the voltage dependent resistors 9 and the components of the voltage divider at quenching of the are between some of the intermediate electrodes 4. In some cases voltage dependent resistors are connected not only between the connections to the intermediate electrodes, but also, by way of example, between the anode and the adjacent intermediate electrode, in which case, however, the voltage dependent resistors of course must be dimensioned for a greater efiect.

FIGURE 2 shows the constructive shaping of a part of the device of FIGURE 1, more exactly, the part between the points A in FIGURE 1. FIGURE 3 shows the device of FIGURE 2 seen from above. The components in FIGURES 2 and 3 are provided with the same reference numbers as in FIGURE 1. 11 are the inlets through the external rectifier casing to the intermediate electrodes. 12 is an isolating supporting pillar. The components are connected by means of bodies 13 which are so shaped that they serve as mechanical as well as electrical connections between the components, and besides this, form are gap electrodes for the arc gaps between the components and the connections respectively. These connection bodies are, when they serve as a connection point to any part of the capacitor 6, attached to this by means of inlets 14 to the capacitor. The connection bodies 13 serving as connection points for the intermediate electrodes 4 in the rectifier, are either fastened directly to the casing of the rectifier 1 by an inlet 11 or to the casing by means of a pin insulator 15, in which case, the connection between the connection bodies 13 and an inlet 11 is made by means of a separate conductor 16. The other connection bodies 13 which only serve as a connection between difierent components in the voltage divider are attached by means of an insulating support 12.

FIGURE 4 shows a form of the connection bodies 13 which are attached to the rectifier casing by means of pin insulators 15. The connection body consists of two substantially spherical halves 17 and 18 of conducting material, which halves are kept together by means of a screw 19 and are attached to the pin insulator 15 by means of a bolt 20. Both halves 17 and 18 are provided with openings in which spring contact terminals 21 and 22 are arranged, which serve as supports as well as electrical connections for the resistors 5. The connection body 13 serves as'mechanical as well as electrical connection for the difierent components in the device and serves besides this, owing to its form, as arc gap electrodes for the arc gaps between the components. If desired, both the halves 17 and 18 could as shown in FIGURES 2 and 3 be provided with salient horns serving as are gap electrodes.

We claim:

1. Anode unit for a high voltage gas-filled rectifier; said anode unit being provided with a number of intermediate electrodes, said intermediate electrodes connected to a voltage divider, said voltage divider consisting of resistors and capacitors and being inserted between the anode and the cathode of the rectifier, voltage dependent resistors inserted between at least some of the connections between said intermediate electrodes and said voltage divider,

2. An arrangement as set forth in claim 1, including ep'ark gaps; said spark gaps being inserted between at least some of the connections between said intermediate electrodes and said voltage divider.

3. An arrangement as set forth in claim 2, including bodies for connection of said voltage dependent resistors and said resistors and capacitors of said voltage divider, said'bod'ies being shaped in order to serve as mechanical as well as electrical connections to the components, and besides this, as spark gap electrodes for said spark gaps between the components.

References fitted in the file of this patent UNITED STATES PATENTS 2,145,727 Lloyd Jan. 31, 1939 2,205,231 Steenback June 18, 1940 2,386,400 Jonas Oct. 9, 1945 

